Visible light sensitive electrodeposition coating composition and image-forming method using the same

Abstract

A composition for visible light sensitive electrodeposition coating which comprises (A) a photocurable resin having light sensitive groups capable of being crosslinked or polymerized by light irradiation and ionic groups, (B) a sensitizer which is excited by absorption of visible light and has a property to interact with the resin (A), (C) a water-insoluble polymerization initiator, and optionally, (D) at least one specific nitrogen-containing compound; and an image-forming method which comprises (i) coating the surface of a conductor by electrodeposition with the aforesaid composition, (ii) exposing the resulting film by electrodeposition by partially irradiating the film with visible light, and then (iii) contacting the resulting film with a developing solution to remove the unexposed areas.

What is claimed is: 
     
       1. A composition for visible light sensitive electrodeposition coating which comprises (A) a photocurable resin having light sensitive groups capable of being crosslinked or polymerized by light irradiation and ionic groups,   (B) a sensitizer which is excited by absorption of visible light and interacts with the resin (A),   (C) a water-insoluble polymerization initiator and   (D) at least one of the nitrogen-containing compounds represented by the following general formulae (1) to (6) ##STR46##  wherein X represents a hydrogen atom or hydroxy group, R 1 , R 2  and R 3  independently represent a hydrogen atom, chlorine atom or alkyl group having 1 to 6 carbon atoms; ##STR47##  wherein R 4  and R 5  independently represent a hydrogen atom, or alkyl group having 1 to 6 carbon atoms; ##STR48##  wherein R 6 , R 7  and R 8  independently represent a hydrogen atom, hydroxyl group or alkyl group having 1 to 12 carbon atoms; ##STR49##  wherein R 9 , R 10  and R 11  independently represent a hydrogen atom, hydroxyl group, alkyl group having 1 to 12 carbon atoms or alkoxy group having 1 to 12 carbon atoms; ##STR50##  wherein R 12  represents a hydrogen atom, hydroxyl group, alkyl having 1 to 12 carbon atoms or alkoxy group having 1 to 12 carbon atoms; ##STR51##  wherein R 13  and R 14  independently represent a hydrogen atom or alkyl group having 1 to 12 carbon atoms and n is an integer of 1 to 3.   
     
     
       2. The composition for electrodeposition coating of claims 1 wherein the light sensitive groups, which the photocurable resin (A) have, are selected from the group consisting of (meth)acryloyl groups, cinnamoyl groups and allyl groups. 
     
     
       3. The composition for electrodeposition coating of claim 1 wherein the content of the light sensitive groups in the photocurable resin (A) ranges from 0.2 to 5.0 moles/kg. 
     
     
       4. The composition for electrodeposition coating of claim 1 wherein the photocurable resin (A) has a glass transition temperature of 0° C. or higher and a number average molecular weight of 300 to 100,000. 
     
     
       5. The composition for electrodeposition coating of claim 1 wherein the photocurable resin (A) is an anionic resin obtained by adding a glycidyl group-containing unsaturated compound to an acrylic resin having a high acid value. 
     
     
       6. The composition for electrodeposition coating of claim 1 wherein the photocurable resin (A) is an anionic resin obtained by reacting a hydroxyl group-containing acrylic resin of a high acid value with a cinnamoyl halide. 
     
     
       7. The composition for electrodeposition coating of claim 1 wherein the photocurable resin (A) is an anionic resin obtained by adding ally glycidyl ether to an acrylic resin having a high acid value. 
     
     
       8. The composition for electrodeposition coating of claim 1 wherein the photocurable resin (A) is a cationic resin having tertiary amino groups or an onium salt in an amount of 0.2 to 5 moles/kg resin. 
     
     
       9. The composition for electrodeposition coating of claim 1 wherein the sensitizer (B) is a dye which is excited by absorption of visible light of 400 to 700 nm. 
     
     
       10. The composition for electrodeposition coating of claim 9 wherein the dye is selected from the group consisting of thioxanthene, xanthene, ketone, thiopyrylium salt, merocyanine, 3-substituted coumalin, cyanine, acridine and thiazine dyes. 
     
     
       11. The composition for electrodeposition coating of claim 1 wherein the amount of the sensitizer (B) to be used ranges from 0.1 to 10 weight parts per 100 weight parts by solid content of the photocurable resin (A). 
     
     
       12. The composition for electrodeposition coating of claim 1 wherein the water-insoluble polymerization initiator (C) has a solubility in water of 2 g/100 ml water or lower. 
     
     
       13. The composition for electrodeposition coating of claim 12 wherein the water-insoluble polymerization initiator (C) is selected from the group consisting of an organic peroxide, an iron-arene complex and a titanocene compound. 
     
     
       14. The composition for electrodeposition coating of claim 12 wherein the water-insoluble polymerization initiator is an iron-allene complex or a titanocene compound. 
     
     
       15. The composition for electrodeposition coating of claim 1 wherein the water-insoluble polymerization initiator (C) is used in a range of 0.1 to 25 weight parts per 100 weight parts of solid content of the photocurable resin (A). 
     
     
       16. The composition for electrodeposition coating of claim 1 wherein the nitrogen-containing compound is the benzotriazole represented by the general formula (1). 
     
     
       17. The composition for electrodeposition coating of claim 16 wherein the nitrogen-containing compound (D) is selected from the group consisting of the benzotriazoles of the following formulae: ##STR52## 
     
     
       18. The composition for electrodeposition coating of claim 1 wherein the nitrogen-containing compound (D) is used in a range of 0.01 to 20 weight parts per 100 weight parts of solid content of the photocurable resin (A).